Oil Pressure issues on 2000 2500 HD

[CLMonti]

A good friend has a 2000 2500 HD (gas) 4x4 with 206k miles. The truck runs fine, however, at start up the oil pressure is almost nonexistant with the gauge ready almost 0. By increasing RPMs at idle the pressure moves toward normal, but when RPMs are reduced it drops back to 0. This is even the case as it is driven for 5 or 10 mins with the engine warm - stop at a light with truck in drive and the pressure drops to almost nothing.

Now, after several miles of straight driving, then stopping at a light, etc. the oil pressure stays consistant when stopped in gear as well as when idle in park. Could this be related to a bad oil sending unit or is it a bad oil pump?

Let me know what other info may be needed.

Thanks,
Chan

[tbplus10]

He needs to use a mechanical gauge to check the oil pressure, once he has a correct reading he can then decide the proper repair.
If the mechanical gauge reads low the oil pump is dying, replace it.
If the mechanical gauge reads a higher pressure the sending unit, wire harness, or gauge could be bad. Test the system with a new gauge or sending unit. The sending unit is the culprit more times than the gauge and wiring.